Embodiments herein are generally drawn to methods of powder coating substrates. Certain embodiments are drawn to substrates (such as, fuser member substrates, among others) coated with outer layers that have a low roll gloss (surface gloss). Some embodiments are drawn to fuser members useful in electrophotographic imaging apparatuses, printers, and the like, having a low gloss outer layer that can be used to produce low gloss prints.
Controlling print gloss is desired by many customers. In general, there are two approaches to achieve different print gloss for printers with a contact fusing system. One is to modify the toner and the other is to modify the fuser member surface. In the electrophotographic printing process, a toner image can be fixed or fused upon a support (e.g., a paper sheet) using a fuser member.
The use of low gloss fuser members (rolls or belts, among others known in the art) to change print gloss has advantages over low gloss toner by enabling a short changeover time, as well as, extending the gloss range that can be obtained. Low gloss prints have been obtained using fluoropolymer and silica aerogel fuser topcoat/outer layers on fuser rolls. Such fluoropolymer/aerogel fuser coatings have been prepared by spray coating solvent dispersions of such coatings and melt-curing. However, the spray coating process results in high variance between samples, due to particle settling. A desirable processing method for production coating of fuser members is powder coating.
Powder coating involves the application of a free flowing, dry powder to a surface, followed by curing. The powder is electrostatically charged, and then directed to a grounded component to form the coating layer. With the application of heat the powder melts and flows to form a cured coating. Powder coating mixtures containing two powders (such as, PFA and aerogel powders) present challenges due to dissimilar densities and flow behavior of the different component powders, and lead to inhomogeneous powder mixtures and changing concentrations of aerogel on coated components.
Curing of mixed fluoropolymer/aerogel coatings is additionally problematic due to inefficient wetting between dissimilar particles upon melting of the fluoropolymer. This leads to a lack of cohesion between the cured surface and the powder coated cured topcoats comprising fluoropolymer particles and aerogel particles. The uneven aerogel concentration that occurs during powder coating and poor wetting between the fluoropolymer and aerogel particles can result in large voids and inclusions. An extra processing step, such as washing of the particles with the addition of surface functionalities, can improve wetting and curing; however, this step promotes little to no association between particles during powder coating. Additionally, it is desirable to avoid the incorporation of extra steps for production coating.
It is desirable, therefore, to produce low gloss prints without the need to change the toner in an electrophotographic imaging apparatus or printer. Further, it is desirable to produce fuser members that are durable and easily manufactured. In addition, a fuser member coating having an even distribution of texture forming particles (e.g., aerogel particles) that enables transfer of toner to form prints of variable gloss is desirable. Certain embodiments herein can address these issues.